What is the approach to managing an abdominal abscess seen on computed tomography (CT) scan in an outpatient setting for a 70-year-old patient with diverticulitis and fever?

From the Guidelines

For a 70-year-old outpatient with diverticulitis, fevers, and a CT-confirmed abdominal abscess, immediate hospital admission is recommended for management, as the presence of an abscess indicates a complicated infection that requires prompt intervention to reduce morbidity and mortality risks. The patient requires IV antibiotics and drainage of the abscess. Initial empiric antibiotic therapy should include piperacillin-tazobactam 3.375g IV every 6 hours or meropenem 1g IV every 8 hours to cover enteric gram-negative bacteria and anaerobes, as suggested by the guidelines for the management of acute left colonic diverticulitis 1.

Key Considerations

• The size of the abscess is a critical factor in determining the need for drainage, with abscesses larger than 4 cm typically requiring percutaneous drainage, as stated in Statement 5.2 of the WSES guidelines 1.
• The patient's clinical response and laboratory values, including WBC count, CRP, and renal function, should be closely monitored to guide the treatment approach.
• Following initial treatment, transition to oral antibiotics (such as amoxicillin-clavulanate 875/125 mg twice daily plus metronidazole 500 mg three times daily) for a total 10-14 day course may be appropriate once clinically improved, as this approach has been shown to be effective in managing complicated diverticulitis 1.

Management Approach

• The American College of Physicians guideline recommends the use of abdominal CT imaging for the diagnosis of acute left-sided colonic diverticulitis, especially when there is diagnostic uncertainty 1.
• The guideline also suggests that clinicians manage most patients with acute uncomplicated left-sided colonic diverticulitis in an outpatient setting, but patients with complicated diverticulitis, such as those with an abscess, require hospitalization and more aggressive management 1.
• The WSES guidelines provide specific recommendations for the management of elderly patients with acute left colonic diverticulitis, including the use of broad-spectrum antibiotic therapy and percutaneous drainage for abscesses larger than 4 cm 1.

Prioritizing Morbidity, Mortality, and Quality of Life

• The management approach should prioritize reducing morbidity and mortality risks, as well as improving the patient's quality of life, by effectively treating the infection and managing any complications that may arise.
• The guidelines emphasize the importance of considering the patient's values and preferences, as well as the potential costs and benefits of different management approaches, in making treatment decisions 1.

From the FDA Drug Label

14 CLINICAL STUDIES 14.1 Complicated Intra-abdominal Infections Adult Patients A total of 979 adults hospitalized with cIAI were randomized and received study medications in a multinational, double-blind study comparing ZERBAXA 1.5 g (ceftolozane 1 g and tazobactam 0. 5 g) intravenously every 8 hours plus metronidazole (500 mg intravenously every 8 hours) to meropenem (1 g intravenously every 8 hours) for 4 to 14 days of therapy. Complicated intra-abdominal infections included appendicitis, cholecystitis, diverticulitis, gastric/duodenal perforation, perforation of the intestine, and other causes of intra-abdominal abscesses and peritonitis.

The approach to an abdominal abscess seen on CT in outpatient care in a 70-year-old with diverticulitis and fevers may involve intravenous antibiotics.

• The ceftolozane-tazobactam regimen has been studied in the context of complicated intra-abdominal infections, including diverticulitis.
• However, the provided study primarily focuses on hospitalized patients, and the patient in question is an outpatient.
• Given the information provided, it is unclear if the patient's condition warrants hospitalization or if outpatient management with antibiotics is sufficient.
• Clinical judgment is necessary to determine the best course of action, considering factors such as the patient's overall health, the severity of the infection, and the presence of any underlying conditions.
• The study results suggest that ceftolozane-tazobactam plus metronidazole is non-inferior to meropenem in terms of clinical cure rates for complicated intra-abdominal infections, including those caused by diverticulitis 2.

From the Research

Approach to Abdominal Abscess in Outpatient Care

• For a 70-year-old patient with diverticulitis and fevers, the approach to an abdominal abscess seen on CT in outpatient care involves considering the size of the abscess and the patient's overall condition 3.
• According to guidelines, diverticular abscesses with diameters larger than 3 cm should be considered for percutaneous drainage, while abscesses with diameters smaller than 3 cm could be appropriately treated by medical therapy with antibiotics 3.
• Conservative treatment with broad-spectrum antibiotics is successful in up to 70% of cases for patients with abscesses, and outpatient management is considered the best strategy in the majority of uncomplicated patients 4.
• CT-guided catheter drainage is an effective method to treat large diverticular abscesses, and overall management is simplified since one-stage sigmoid resection can be performed electively on a non-septic patient 5.

Antibiotic Treatment

• The choice of antibiotic treatment for diverticulitis is important, and options include metronidazole-with-fluoroquinolone or amoxicillin-clavulanate 6.
• A study found that treating diverticulitis in the outpatient setting with amoxicillin-clavulanate may reduce the risk for fluoroquinolone-related harms without adversely affecting diverticulitis-specific outcomes 6.
• Another study found that ceftriaxone and metronidazole was non-inferior to piperacillin/tazobactam for the combined primary outcome of 30-day readmission or all-cause mortality in patients with complicated diverticulitis 7.

Considerations for Outpatient Care

• Outpatient management is considered the best strategy in the majority of uncomplicated patients, and high-risk patients may be spared surgery entirely in selected cases 4, 5.
• The patient's overall condition, including the presence of fevers and the size of the abscess, should be taken into account when deciding on the approach to care 3.